The general objective of the proposed study is to determine the mechanisms by which batteries of genes are regulated. The first chapter is directed to resolving the relationship between genome structure and regulation of a specific battery of genes which are induced by heat shock treatment of Drosophila melanogaster cells. This treatment greatly simplifies the pattern of gene expression, in that most preexisting gene expression is repressed, while several previously unexpressed genes are activated. This rapid change in gene expression is a consequence of dramatic changes in both the cell's transcriptional and translational activity. These coordinately inducible genes are located at several different sites in the genome; and therefore, each should possess its own gene regulator. The specific objectives are: 1) to isolate the heat shock inducible genes and their flanking sequences by the use of recombinant DNA techniques; 2) to characterize both gene and flanking sequences with respect to their repetition frequency and arrangement in the genome; 3) to map regulatory nucleotide sequences with respect to transcription initiation sites for these genes. The second chapter is directed to developing a method of screening cloned D. melanogaster DNA segments for those segments derived from regions of the genome that code for regulators of developmental processes. The screening method will be adapted from the analytical method of in situ hybridization to polytene chromosomes, and it will be tested in reconstruction experiments using characterized recombinant DNAs.